void setup() {
  // put your setup code here, to run once:
  Serial.begin(1200);
}

void loop() {
  // put your main code here, to run repeatedly:
  dt = 1234;
  dtH = dt & 0x700; //3 bit
  dtH = dtH >> 8;
  dtL = dt & 0x0ff; //8bit
  Serial.write(dtH);
  Serial.write(dtH);
  delay(100); // this speeds up the simulation
}